In a major advance in the fight against HIV/AIDS, the Food and Drug Administration has approved the marketing of the antiretroviral drug Truvada for the prevention of HIV transmission, according to the San Francisco Chronicle. This comes after a panel of experts recommended in May 2012 that the FDA approve the drug's use as a prevention method for healthy people.

While the drug was approved in 2004 to treat those already infected with the virus, studies have shown that Truvada may also help prevent the spread of HIV among high-risk individuals, including men who have sex with men and people with HIV-positive partners.

Truvada, which is actually a combination of two medicines, works by blocking the enzyme in the body that the HIV virus needs to multiply.

Results of the UCSF-led study showed that, when taken daily and stacked up against a placebo, the drug reduced the risk of HIV infection by 42 percent among HIV-negative men or transgender women who had unprotected sex with multiple partners, including some HIV carriers.

In another trialinvolving heterosexual couples in which one partner was infected, the drug reduced the risk of infections by 75 percent.

"It's about time we had something aggressive to prevent HIV," said Dr. Lisa Sterman, an HIV clinician and researcher at California Pacific Medical Center in San Francisco. "We can't get any further with prevention messages and condoms."

Sterman has already started prescribing the drug to some of her high-risk patients for prevention when possible. But she said the approval means that the drug can get covered through health insurance for those who are not diagnosed with HIV.

Used daily, Truvada will cost $13,900 a year, according to a Gilead Sciences spokeswoman.

UCSF's Grant said he considers the drug to be cost-effective when compared to the expense of medical complications and lifelong drugs to treat HIV and AIDS. But he said the drug's use must be carefully prescribed as well as monitored by a physician.

"It's highly effective if used consistently, but it does require daily use and people need to think realistically about whether they can take a tablet every day," he said, adding that people must also be able to recognize they need it.